Cl Type Research Articles

Groundwater quality in Sargodha City, Pakistan: Comprehensive research of geochemical modeling, groundwater quality assessment, and risk evaluation

Groundwater, an indispensable global resource, faces escalating contamination threats, jeopardizing human health and environmental sustainability. This study offers detailed insights into the quality of the groundwater, its drinking suitability, and associated human health risks in Sargodha City, Pakistan. Employing hydrogeochemical analysis, inverse geochemical modeling, groundwater quality index, and human health risk evaluation, this research highlights widespread exceedances of WHO drinking water standards, particularly in TDS, EC, TH, Na+, Ca2+, Mg2+, SO42−, Cl−, HCO3−, NO3–N, and As levels, signifying that a significant portion of the groundwater is unfit for consumption. Hydrochemical facies analysis reveals a dominance of the Na–Cl type. Water–rock interactions, cation exchange, and anthropogenic influences are the primary factors shaping groundwater hydrochemistry in the region. Saturation indices and inverse geochemical modeling demonstrated intricate geochemical processes involving both mineral precipitation and dissolution. Notably, the GWQI reveals a diverse spectrum of water quality, with 50% of the samples exhibiting excellent to good quality, 29% falling into the poor to extremely poor category, and 21% deemed unfit for drinking. Health risk assessment reveals alarming carcinogenic risks from As, affecting children (70.8%) and adults (83.35%), while 8.3% of the samples indicate non-carcinogenic risks. Conversely, NO3–N presents acceptable non-carcinogenic risks across all samples. The total hazard index spans between 0.14 and 1.90 for adults and 0.16 to 2.23 for children, underscoring the heightened vulnerability of children. This study advances the understanding of groundwater contamination dynamics in urbanized regions, offering insights to safeguard public health and ensure sustainable water management in areas with similar hydrogeochemical conditions.

Appraisal of groundwater suitability for drinking and irrigation utilities in the Cooum River basin, South India: Implications from uranium, nitrate, and fluoride health risks

The study reveals that 6% of groundwater samples exceed the WHO's recommended fluoride limit of 1.5 mg/L, and 15% surpass the nitrate standard of 45 mg/L, rendering the water unsuitable for drinking. Gibbs plot analysis identifies evaporation as the dominant factor affecting groundwater chemistry, while the Piper diagram classifies the water into mixed Ca–Mg–Cl and NaCl types, indicating natural processes and potential seawater intrusion. Cation exchange processes are observed in 75.5% of samples, as shown by Schoeller's indices. The hydrochemical facies evolution suggests freshening from recharge in most samples, with signs of salinity intrusion in others. Between 2010 and 2023, land use and land cover (LULC) changes show a significant increase in built-up areas, resulting in reduced groundwater recharge and heightened pollution risks. The classification accuracy is high, with an overall accuracy of 82.20% and a Kappa coefficient of 83.06%. Water Quality Index (WQI) assessment reveals that 47% of the groundwater samples are excellent for drinking, while 20.6% are suitable. Although 80% of the groundwater remains appropriate for agriculture, the study highlights the need for targeted groundwater management to address urbanization impacts and mitigate health risks from elevated nitrate ingestion, particularly for vulnerable populations such as children.

Fluid evolution and genesis of the Shipenggou gold deposit in Central Jilin Province, China: Constraints from C–H–O and in–situ sulphur isotopes of pyrite and fluid inclusions

The origin and evolution of the Shipenggou gold deposit in the Shipenggou–Jiapigou–Jinchengdong (SJJ) gold belt in Jilin Province, Northeast China, remain poorly understood. In this study, fluid inclusion and C–H–O–S isotopes from the Shipenggou deposit were investigated to clarify the fluid evolution and mineralisation process. The gold mineralisation is hosted in the biotite plagiogneiss of the Archaean Sandaogou Formation and is dominated by gold–bearing quartz veins. The orebodies are controlled by NNE– and NEE–striking brittle–ductile structures. Four stages of mineralisation have been identified: (I) milky quartz–minor pyrite, (II) quartz–pyrite–minor gold, (III) gold–quartz–polymetallic sulphide, and (IV) quartz–carbonate. Fluid inclusions were identified as four types: aqueous (VL–type), CO2–bearing (CL–type), CO2–rich (LC–type), and carbonic (PC–type). VL–, CL–, LC–, and PC–type FIs were developed within quartz from Stages I–II. Stage III quartz contains both CL– and VL–type FIs. Only VL–type FIs were observed in calcite from Stage IV. The total homogenisation temperatures (Tht) of FIs in Stages I, II, III, and IV are of 281.5–324.8, 215.5–269.1, 151.2–198.3, and 125.4–149.5 °C with salinities of 2.8–13.2, 2.8–9.6, 3.2–8.4, and 3.0–5.9 wt% NaCl eqv. Laser Raman spectroscopy analysis indicated the CL– and PC–type FIs from Stages I and II contain CO2 and minor quantities of CH4. The ore–forming fluids have developed from a medium temperature, low–medium salinity immiscible NaCl–H2O–CO2 ± CH4 system to a low temperature, low salinity homogeneous NaCl–H2O system. The HO isotopic compositions indicate that the initial ore–forming fluids were mantle–derived magmatic water. Subsequently, the ore–forming fluids were gradually joined by meteoric water. δ13C values indicate C in the fluids have originated from organic matter. Organic matter may have originated from the mantle, which mixed crust materials influenced by the subduction of the Palaeo–Pacific slab. In–situ, S isotope data of pyrite indicate that the origin of sulphur at the Shipenggou deposit is the mantle containing a crust component. Based on the above analysis results, the Shipenggou gold deposit is a mesothermal magma-hydrothermal vein–type gold deposit.

Crystal structures of two unexpected products of vicinal diamines left to crystallize in acetone.

Herein we report the crystal structures of two benzodiazepines obtained by reacting N,N'-(4,5-diamino-1,2-phenylene)bis(4-methylbenzenesulfonamide) (1) or 4,5-(4-methylbenzenesulfonamido)benzene-1,2-diaminium dichloride (1·2HCl) with acetone, giving 2,2,4-trimethyl-8,9-bis(4-methylbenzenesulfonamido)-2,3-dihydro-5H-1,5-benzodiazepine, C26H30N4O4S2 (2), and 2,2,4-trimethyl-8,9-bis(4-methylbenzenesulfonamido)-2,3-dihydro-5H-1,5-benzodiazepin-1-ium chloride 0.3-hydrate, C26H31N4O4S2+·Cl-·0.3H2O (3). Compounds 2 and 3 were first obtained in attempts to recrystallize 1 and 1·2HCl using acetone as solvent. This solvent reacted with the vicinal diamines present in the molecular structures, forming a 5H-1,5-benzodiazepine ring. In the crystal structure of 2, the seven-membered ring of benzodiazepine adopts a boat-like conformation, while upon protonation, observed in the crystal structure of 3, it adopts an envelope-like conformation. In both crystalline compounds, the tosylamide N atoms are not in resonance with the arene ring, mainly due to hydrogen bonds and steric hindrance caused by the large vicinal groups in the aromatic ring. At a supramolecular level, the crystal structure is maintained by a combination of hydrogen bonds and hydrophobic interactions. In 2, amine-to-tosyl N-H...O and amide-to-imine N-H...N hydrogen bonds can be observed. In contrast, in 3, the chloride counter-ion and water molecule result in most of the hydrogen bonds being of the amide-to-chloride and ammonium-to-chloride N-H...Cl types, while the amine interacts with the tosyl group, as seen in 2. In conclusion, we report the synthesis of 1, 1·2HCl and 2, as well as their chemical characterization. For 2, two synthetic methods are described, i.e. solvent-mediated crystallization and synthesis via a more efficient and cleaner route as a polycrystalline material. Salt 3 was only obtained as presented, with only a few crystals being formed.

Enhanced thermal and water stability of halide perovskite MAPbBr3 by double-coated hydrogen-bonded polymer network

MAPbX3 (X = Br, I, Cl) type lead halide perovskite has great potential for light-emitting devices due to its excellent optical properties; however, their degradation under the influence of heat and atmospheric moisture severely limited their applications. To address this issue, we used a dynamic hydrogen bonding network constructed by amino-terminated hyperbranched aminoglycoside polymer (AHP) and thermoplastic polyurethane (PUIP) to double-coat MAPbBr3. The thermal and water degradation of MAPbBr3 was greatly alleviated upon formation of the MAPbBr3@AHP@PUIP composite. The structures of AHP, PUIP, MAPbBr3@AHP, and MAPbBr3@AHP@PUIP films were characterized by various techniques. The double-coated MAPbBr3@AHP@PUIP film exhibited high quantum efficiency and excellent luminescence stability at room temperature, with quantum yields remained above 90 % of the original value even after 20 days in air. Moreover, the polymer film still maintains high fluorescence emission after 72 h in the water phase, and can achieve fluorescence recovery transformation at a specific temperature, and has a good self-healing property at room temperature. This inexpensive and convenient method not only greatly enhanced PL efficiency, increased water stability, but also demonstrated excellent flexibility and elasticity, suggesting broad prospects for the commercial application of inorganic perovskite materials in flexible electronics.

Assessment of hydrochemical characteristics, health risks and quality of groundwater for drinking and irrigation purposes in a mountainous region of Pakistan

Renowned for its agriculture, livestock, and mining, Zhob district, Pakistan, faces the urgent problem of declining groundwater quality due to natural and human-induced factors. This deterioration poses significant challenges for residents who rely on groundwater for drinking, domestic, and irrigation purposes. Therefore, this novel study aimed to carry out a comprehensive assessment of groundwater quality in Zhob district, considering various aspects such as hydrochemical characteristics, human health risks, and suitability for drinking and irrigation purposes. While previous studies may have focused on one or a few of these aspects, this study integrates multiple analyses to provide a holistic understanding of the groundwater quality situation in the region. Additionally, the study applies a range of common hydrochemical analysis methods (acid–base titration, flame atomic absorption spectrometry, and ion chromatography), drinking water quality index (WQI), irrigation indices, and health risk assessment models, using 19 water quality parameters. This multi-method approach enhances the robustness and accuracy of the assessment, providing valuable insights for decision-makers and stakeholders. The results revealed that means of the majority of water quality parameters, such as pH (7.64), electrical conductivity (830.13 μScm–1), total dissolved solids (562.83 mgL–1), as well as various anions, and cations, were in line with drinking water norms. However, the water quality index (WQI) predominantly indicated poor drinking water quality (range = 51–75) at 50% sites, followed by good quality (range = 26–50) at 37% of the sites, with 10% of the sites exhibiting very poor quality (range = 76–100). For irrigation purposes, indices such as sodium percent (mean = 31.37%), sodium adsorption ratio (mean = 0.98 meqL–1), residual sodium carbonate (– 3.15 meqL–1), Kelley’s index (mean = 0.49), and permeability (mean = 49.11%) indicated suitability without immediate treatment. However, the magnesium hazard (mean = 46.11%) and potential salinity (mean = 3.93) demonstrated that prolonged application of groundwater for irrigation needs soil management to avoid soil compaction and salinity. Water samples exhibit characteristics of medium salinity and low alkalinity (C2S1) as well as high salinity and low alkalinity (C3S1) categories. The Gibbs diagram results revealed that rock weathering, including silicate weathering and cation exchange, is the primary factor governing the hydrochemistry of groundwater. The hydrochemical composition is dominated by mixed Ca–Mg–Cl, followed by Na–Cl and Mg–Cl types. Furthermore, the human health risk assessment highlighted that fluoride (F–) posed a higher risk compared with nitrate (NO3–). Additionally, ingestion was found to pose a higher risk to health compared to dermal contact, with children being particularly vulnerable. The average hazard index (HI) for children was 1.24, surpassing the allowable limit of 1, indicating detrimental health effects on this subpopulation. Conversely, average HI values for adult females (0.59) and adult males (0.44) were within safe levels, suggesting minimal concerns for these demographic groups. Overall, the study’s interdisciplinary approach and depth of analysis make a significant contribution to understanding groundwater quality dynamics and associated risks in Zhob district, potentially informing future management and mitigation strategies.

Application, structure, salts and complexes of lidocaine: a review. Part V. structure of bis(lidocaine) tetrachloridocuprate(II)

The review focuses on lidocaine (2-(diethylamino)-N-(2,6-dimethylphenyl)acetamide): in the first part, its use in various branches of medicine, as well as the structure of lidocaine, its salts and molecular complexes was discussed; in the second part the use of lidocaine in the composition of deep-eutectic solvents (DES), DES-microemulsions and complexes of lidocaine with zinc, copper, cobalt, platinum and iron was considered; in the 3rd the structure of bis(lidocaine) tetrachlorido-zincate(II) was considered, in the 4th part the structure of bis(lidocaine) tetrachloridoferrate(III) chloride was discussed, this part reports on the synthesis and structure of bis(lidocaine) tetra-chloridocuprate(II), (LidH)2[CuCl4], which crystallizes in the monoclinic space group P21/c with a = 15.7831(2), b = 24.2992(2), c = 17.8748(2) Å, β = 104.874(1)°, V = 6625.58(13) Å3, Z = 8, and Dc = 1.355 Mg/m3. The coordination of the Cu2+ ions with chlorine atoms generates two differently distorted tetrahedral anions [CuCl4]2–, while four protonated cations LidH+ remain in an outer coordination sphere. Anions and cations are associated by hydrogen bonds of the N–H···Cl type to form the 2{(LidH)2[CuCl4]} dimer, in which the distance between two copper atoms is 8.95 Å (c/2). With the help of hydrogen bonds of the type N–H···O and N–H·Cl, each dimer is connected with four neighboring dimers, resulting in a three-dimensional structure in which dimers lie at an angle of 28.39° to the a crystallographic axis in the ab planes located at a distance of 10.67 Å from each other.

Comprehensive approach integrating remote sensing, machine learning, and physicochemical parameters to detect hydrodynamic conditions and groundwater quality deterioration in non-rechargeable aquifer systems

The current study integrates remote sensing, machine learning, and physicochemical parameters to detect hydrodynamic conditions and groundwater quality deterioration in non-rechargeable aquifer systems. Fifty-two water samples were collected from all water resources in Siwa Oasis and analyzed for physical (pH, T°C, EC, and TDS) chemical (SO42−, HCO3−, NO3−, Cl−, CO32−, SiO2, Mg2+, Na+, Ca2+, and K+), and trace metals (AL, Fe, Sr, Ba, B, and Mn). A digital elevation model supported by machine learning was used to predict the change in the land cover (surface lake area, soil salinity, and water logging) and its effect on water quality deterioration. The groundwater circulation and interaction between the deep aquifer (NSSA) and shallow aquifer (TCA) were detected from the pressure-depth profile of 27 production wells penetrating NSSA. The chemical facies evolution in the aquifer systems were (Ca–Mg–HCO3) in the first stage (freshwater of NSSA) and changed to (Na–Cl) type in the last stage (brackish water of TCA and springs). Support vector machine successfully predicted the rapid increase of the hypersaline lake area from 22.6 km2 to 60.6 km2 within 30 years, which deteriorated a large part of the cultivated land, reflecting the environmental risk of over-extraction of water for irrigation of agricultural land by flooding technique and lack of suitable drainage network. The waterlogging in the study was due to a reduction in the infiltration rate (low permeability) of the soil and quaternary aquifer. The cause of this issue could be a complete saturation of agricultural water with chrysotile, calcite, talc, dolomite, gibbsite, chlorite, Ca-montmorillonite, illite, hematite, kaolinite and K-mica (saturation index >1), giving the chance of these minerals to precipitate in the pore spaces of the soil and decrease the infiltration rate. The NSSA is appropriate for irrigation, whereas TCA is inappropriate due to potential salinity and magnesium risks. The best way to manage water resources in Siwa Oasis could be to use underground drip irrigation and combine water with TCA and NSSA.

Hydrogeochemical evolution and water–rock interaction processes in the multilayer volcanic aquifer of Yogyakarta-Sleman Groundwater Basin, Indonesia

Volcanic aquifers have become valuable resources for providing water to approximately 2.5 million people in the Yogyakarta-Sleman Groundwater Basin, Indonesia. Nevertheless, hydrogeochemical characteristics at the basin scale remain poorly understood due to the complexity of multilayered aquifer systems. This study collected sixty-six groundwater samples during the rainy and dry seasons for physicochemical analysis and geochemical modeling to reveal the hydrogeochemical characteristics and evolution in the Yogyakarta-Sleman Groundwater Basin. The results showed that groundwater in the unconfined and confined aquifers exhibited different hydrogeochemical signatures. The Ca–Mg–HCO3 facies dominated groundwater from the unconfined aquifer. The groundwater facies evolved into a mixed Ca–Mg–Cl type along the flow direction towards the discharge zone. Meanwhile, groundwater from the confined aquifer showed mixed Ca–Na–HCO3, Na–HCO3, and Na–Cl–SO4 facies. The presence of Mg in the confined aquifer was replaced by Na, which was absorbed in the aquifer medium, thus showing the ion exchange process. The main geochemical processes can be inferred from the Gibbs diagram, where most groundwater samples show an intensive water–rock interaction process mainly influenced by the weathering of silicate minerals. Additionally, only groundwater samples from the confined aquifer were saturated with certain minerals (aragonite, calcite, and dolomite), confirming that the groundwater followed the regional flow system until it had sufficient time to reach equilibrium and saturation conditions. This study successfully explained the hydrogeochemical characteristics and evolution of a multilayer volcanic aquifer system that can serve as a basis for groundwater basin conservation.

Effects of mine water discharge on river sediments: metal fate and behaviour, Upper Silesian Coal Basin

The study aims to characterise the changes in elemental composition in the river sediments of streams influenced by mine waters enriched with radionuclides. The study took place in the vicinity of Ostrava, a city located in a coal mining region in the Czech Republic, namely the Upper Silesian Coal Basin. River sediments and waters of the Karvinský potok and Stružka streams were investigated. Field measurements were made for ambient dose equivalent rate (ADER). Laboratory gamma spectrometry and X-ray fluorescence were used to determine the content of radionuclides and elemental composition in river sediments. Water samples were analysed for the content of major ions and radionuclides. The field ADER measurement proved elevated content of radionuclides with values exceeding 1,000 nSv/h in both streams. The discharged mine waters were Na–Cl type, containing an 226Ra (0.68–0.70 Bq/l) as a dominant radionuclide. Laboratory measurements of radionuclides in bottom sediments proved that the prevailing source of radiation are 226Ra and 232Th in both streams. The calculated enrichment factors showed extreme values for Sr, Cr, Pb, Zn, Cu, and Mo. The precipitation reactions forming Ca-minerals (calcite and aragonite), Fe-bearing minerals (hematite, goethite and amorphous Fe(OH)3) and hausmannite were found to be the primary geochemical process underway in the studied riverine systems. The correlation between elements and radionuclides demonstrated the significant role of geochemical barriers that lead to the precipitation of radionuclides from solution. The results show that the precipitation takes place preferentially in places where other waters enter the stream, or where recent organic matter is present.

Hydro-chemical characteristics and groundwater quality evaluation in south-western region of Bangladesh: A GIS-based approach and multivariate analyses

The study focuses on the chemistry of groundwater and if it is suitable for drinking and for use in agriculture using water quality indices, GIS mapping, and multivariate analyses in Sharsa Upazila, Jashore district, Bangladesh. In this study, the concentration of NH4+, K+, Ca2+, EC, Turbidity overstep BDWS drinking standards in 69 %, 14 %, 100 %, 40 % (WHO), 73 % of samples respectively. The value of Water Quality Indices (WQI) results inferred that the maximum specimen was held good quality for drinking uses, and the values distributed central eastern part to the south-eastern part were good quality water in the selected studied area. The study area's PH, EC, SAR, Na (%), TH, and NO3− values were mapped using GIS tools to show their spatial distribution. The cluster and correlation matrix analyses are used to validate for Principle Component Analysis (PCA). The five PCA results exhibited that the presence of EC, turbidity, K+, SO42− and NO3− was significant and was caused by both geogenic (rock weathering and cation exchange) and anthropogenic (agrochemicals, animal feedback) factor. According to the hydro-geochemical data, the maximum number of samples is of the Ca–Mg–HCO3–Cl type and is dominated by rocks. The irrigation water indices like MH, KR, SAR, and %Na indicate show high-quality groundwater for irrigation purposes. Most of the samples were satisfactory and compiled with WHO and Bangladeshi criteria for standard drinking water guideline values.

Synthesis, Crystal Structure, Hirshfeld Surface Analysis, Energy Framework Calculations, and Halogen Bonding Investigation of Benzene-1,3,5-triyltris((4-chlorophenyl)methanone)

We synthesized 1,3,5-triyltris((4-chlorophenyl)methanone) by a condensation reaction in glacial acetic acid and studied utilizing spectroscopic and analytical techniques such as ultraviolet, infrared, mass, elemental, and nuclear magnetic resonance (NMR) spectroscopy, as well as X-ray crystallography. The effect of chlorine substitution in the 1,3,5-triaroylbenzene compound in solid-state arrangements was studied. Halogen bonds are detected in the solid-state structures of the titled compound. A dimeric structure is formed due to the presence of two C-Cl···Cl Type I halogen interactions. Additionally, a delocalized Type III C-Cl···π interaction were reported. C-Cl···H hydrogen bonding and π···π interaction were also reported. Hirshfeld surface analysis, 3D fingerprint, the energy framework, and the electro-optic potential were used to evaluate such interactions.

Hydrochemistry, controlling mechanisms and water quality index in hot springs of the Kullu-Manali region, India

The present study highlights the unique chemical characteristics of hot springs and their comparison with cold springs, surface water, and groundwater in the same area. The hot springs' temperature ranges from 27 to 96 °C, which induce variable degree of hydrochemical alteration of hot springs' water. The concentrations of Na+ and K+ are highly correlated with Cl−, HCO3−, and SO42− in hot springs, while Ca2+ and Mg2+ behave erratically. The Na/Cl ionic ratios give clues of a restricted geological environment of thermal waters, mixing in cold springs and groundwater, and a meteoric origin of the surface water. The SiO2 behave conservatively, with little change in different water types except surface water. The concentrations of SiO2, highest in the hot springs and lowest in the surface water, help draw depth profiling of different water types. Mixing of ascending hot springs with overlying waters of different origins creates ambiguity in chemical interpretations. Due to mixing with different water types, Chalcedony thermometry better represents hot springs than Na–K–Mg geothermometry. As a result, hot springs alter from Na–Cl and Na–Cl–SO4 type facies with high SiO2 and gradually evolved in Ca–Mg–Na–HCO3–Cl type water. Similarly, most cold springs show mix-type and Ca–HCO3 water types. The chemical characteristics of cold springs are similar to groundwater and equally sensitive to seasonal variation due to mixing with meteoric recharge. The surface water is characterized by Ca–Cl2 type water. All water types acquire unique chemical signatures due to the combined effect of geological formations, depth, temperature, degree of meteoric recharge, and, to some extent, anthropogenic pollution. The Water Quality Index (WQI) assessment revealed that three samples from the Kullu and Kalath regions fall in poor WQI, requiring immediate protection from anthropogenic pollution.

Hydrogeochemical and qualitative assessment of groundwater in a southern Mediterranean region: an example of the Aïn Témouchent area (northwestern Algeria)

Abstract The present research aims to assess the hydrogeochemical processes, the suitability of groundwater for human consumption, and the influence degree of seawater intrusion of the coastal aquifers of the Aïn Témouchent region (northwestern Algeria). In this context, 29 groundwater samples were taken during April–May 2018 and analyzed for 11 physicochemical parameters. Piper and Chadha's diagrams allowed the identification of Na–Cl dominant hydrogeochemical facies and Ca (Mg)–Cl type facies, indicating the influence of salt water. Simpson's Index results highlighted that groundwater was slightly contaminated by saltwater. Obtained values of the seawater mixing index (SMI) and Cl−/(HCO3−), Na+/Cl− and Ca2+/Mg2+ ratios indicated the majority of the sampling sites are affected by seawater intrusion. The integration of the water quality index (WQI) spatial variation through the geographic information system (GIS) indicated that in the Southern part of the study region, and 55.2% of water samples are suitable as drinking water. Adversely, for the northern part, where groundwater is influenced by seawater intrusion, water sampling points fall into bad and very bad categories. The results of the study show that hydrogeochemical processes are responsible for the salinity of groundwater in the study area, in addition to marine intrusion.

Synthesis, spectral, thermal properties, and crystal structure of bis(2,4-dichlorobenzoato-O)bis(thiourea-S)zinc(II)

AbstractThe complex compound bis(2,4-dichlorobenzoato-O)bis(thiourea-S)zinc(II) has been prepared and characterized by elemental analysis, thermal analysis, IR spectroscopy, and single-crystal X-ray analysis. During the thermal decomposition in inert atmosphere, thiourea, dichlorobenzene and carbon dioxide are evolved. The solid intermediate was confirmed by IR spectroscopy, and the final product of the thermal decomposition was proven by powder diffractometry. The coordination environment of the zinc(II) atom is built up by two sulphur atoms from two thiourea ligands and two oxygen atoms from two monodentate 2,4-dichlorobenzoate anions to form a distorted tetrahedral coordination around the zinc(II) atom (chromophore ZnO2S2). The mode of the carboxylate binding was assigned from the IR spectrum using the magnitude of the separation between the carboxylate stretches (Δ), and it is in good agreement with the crystal structure. The structure is also stabilized with hydrogen bonds of N–H···O and N–H···Cl type.

Spatial characteristics of hydrochemistry and stable isotopes in river and groundwater, and runoff components in the Shule River Basin, Northeastern of Tibet Plateau

Water resources play a crucial role in constraining the high-quality development of the arid, necessitating an in-depth investigation and understanding of hydrological processes, hydrochemical characteristics, and their influencing factors amidst climate change. This study meticulously examined and analyzed the hydrochemistry and stable isotope composition (δ18O and δD) of river and groundwater within the Shule River Basin (SRB). Results showed that both river (mean: 8.01) and groundwater (mean: 7.92) had alkaline pH values, while average total dissolved solids were measured at 709.25 mg/L in river and 861.88 mg/L in groundwater, indicating predominance of fresh water sources. HCO3−, SO42−, Na+ and Ca2+ were the most abundant ions, influenced by evaporation-crystallization processes and rock weathering. The dominated hydrochemical facies in both river and groundwater were Ca–HCO3 type in the upper (UR) and the middle reaches (MR), while Ca–Mg–Cl type in the lower reaches (LR). The local meteoric water line (LMWL) was defined as δD = 8.01δ18O + 18.48 (R2 = 0.98, n = 163; P < 0 0.001). The more negative δ18O and δD values in river and groundwater were plotted nearby and lower right of the LMWL, implying that the important recharge source of those waters is from precipitation. The relationship between river δ18O and elevation showed an increase of 0.14‰/100 m in the UR, but a negative correlation with a rate of −0.47‰/100 m in the MR and LR. Precipitation, groundwater, baseflow and meltwater accounted for 62.5%, 19.8%, 11.9% and 5.8% of the UR river, respectively, during the observed period, according to the end-member mixing analysis. These runoff components displayed distinct seasonal variations, primarily driven by precipitation during the early and groundwater/baseflow during the rapid and end-stage ablation periods. The observed alterations in hydrological elements present both opportunities and challenges for water resource management across the SRB, and adaptive measures have been proposed based on our study. These findings provide valuable insights into efficient utilization of water resources from water chemistry and environmental isotopes.

Application of radium isotopes to estimate seawater intrusion rate in coastal aquifers

Coastal aquifers, as the interface zone between ocean and land, are highly sensitive and vulnerable to seawater intrusion. This study presents the behavior of radium isotopes and their application to estimate the rate of seawater intrusion in a typical coastal city (Qinhuangdao, China). The hydrochemical results indicated that the coastal aquifers have Na–Cl type water with the lower Na/Cl ratios. The analysis revealed that the formation process of the chemical composition of groundwater was mainly the mixing of seawater and groundwater, while that of inland groundwater was dominated by mineral dissolution and cation exchange and adsorption. Groundwater of intruded aquifers contain significantly higher activities of radium than those of nearshore seawater and inland groundwater. The rates of seawater intrusion were estimated by using equation of the fate and transport of radium in 1–D transient groundwater flow system. In the calculation process, we ignored dissolution and co-precipitation and mainly considered mixing, alpha recoil and decay contribution for radium activity as sources and sinks terms of radium in coastal groundwater based on the characteristics of radium activity and 224Ra/228Ra ratio in groundwater. The recoil (P) was determined by the activity ratio of 224Ra to Th (232Th/230Th), while the retardation (Rf) was calculated from the steady-state radium equilibrium equation. The seawater intrusion rates were obtained by integrating 224Ra and 228Ra activities under different thorium ratios (232Th/230Th). The results show that the rate of seawater intrusion varies in a wide range at different locations, which are 0.17–1.03 (232Th/230Th = 0.67) and 0.11–1.01 (232Th/230Th = 1.25) m/d. The method of calculating seawater intrusion rate with radium isotope can obtain the rate of different parts of heterogeneous anisotropic aquifer, which also extends the application of radium isotope in hydrogeology.

Groundwater quality, human health risks and major driving factors in arid and semi-arid regions of Rajasthan, India

Evaluating status, variability and identifying the factors influencing groundwater quality is essential to manage and conserve groundwater resources. The present study aims to examine groundwater quality for 15 water quality parameters from 84 stations in arid and semi-arid districts of Rajasthan, India, using annual data from 2000 to 2018. Statistical methods such as descriptive test statistics, Mann-Kendall (MK) test, Sen’s slope estimation, and Principal component analysis (PCA) were used to analyze the hydrochemical parameters. While World Health Organisation (WHO) and Bureau of Indian Standards (BIS) guidelines were used to assess the suitability of groundwater for domestic purposes, sodium adsorption ratio (SAR), electrical conductivity (EC), and United States Salinity (USSL) diagrams were used for irrigation suitability. Further Generalized Additive Model (GAM) was used to explore the effect of climatic (precipitation, temperature) and anthropogenic (net irrigated area (NIA), fertilizer usage, industrialization, and population) variables on groundwater quality. The empirical results reveal that in groundwater of the study area sodium (Na+) and potassium (K+) were the dominating cations, while chloride (Cl−) and bicarbonate (HCO3−) were the dominating anions. The groundwater was predominantly Na–Cl type. Further, most stations witnessed an increasing trend in calcium, magnesium, sodium, chloride, bicarbonate and sulphate and a decreasing trend in potassium, fluoride and nitrate. The SAR, EC, and USSL indicate that the groundwater in the region is suitable for irrigation if salinity control measures are implemented. Chloride, fluoride and sodium concentrations exceeded the prescribed guideline limits in most stations, jeopardizing the suitability of water for drinking and posing significant health hazards. The GAM analysis revealed that anthropogenic variables significantly impact the groundwater quality parameters compared to the climatic variables. Accordingly, it is suggested that anthropogenic parameters must be addressed while formulating groundwater resource management policies. Thus, policies should focus on the stringent enactment of regulations and guidelines controlling the excessive use of fertilizers, implementing proper disposal of municipal solid and liquid waste, and managing industrial pollutants.

Identifying the hydrochemical features, driving factors, and associated human health risks of high-fluoride groundwater in a typical Yellow River floodplain, North China.

Fluoride enrichment (> 1.5mg/L) in groundwater has become a global threat, particularly given the hazards to human health. This study collected 58 unconfined groundwater samples from Fengpei Plain in June 2022 for hydrochemical and stable isotope analyses combined with multiple methods to explore sources, influencing factors, and potential health hazards of groundwater F-. The results showed that groundwater F- concentration ranged from 0.08 to 8.14mg/L, with an average of 1.91mg/L; over 41.4% of them exceeded the acceptable level of 1.5mg/L prescribed by the World Health Organization (WHO). The dominant hydrochemical facies changed from Ca·Mg-HCO3 and Ca·Mg-SO4·Cl type in low-F- groundwater to Na-HCO3 and Na-SO4·Cl water types in high-F- groundwater. The Self-Organizing Map (SOM) and ionic correlation analysis indicated that F- is positively correlated to pH, EC, Na+, K+, SO42-, and TDS, but negatively to Ca2+ and δ18O. Groundwater F- accumulation was primarily driven by F--bearing minerals dissolution such as fluorite. Simultaneously, the carbonates precipitation, positive cation exchange processes, and salt effect were conducive to groundwater F- enrichment. However, competitive adsorption between OH-/HCO3- and F-, evaporation, and anthropogenic activities only had a weak effect on the F- enrichment in groundwater. The hazard quotient (HQ) assessment results show that 67.2% of groundwater samples pose a non-carcinogenic risk (HQ > 1) for infants, followed by 53.4% for children, 32.8% for females, and 25.9% for males. The Monte Carlo simulation results agreed with those of the deterministic model that minors are more susceptible than adults. These findings are vital to providing insights into the geochemical behavior, driving factors, and drinking water safety of high-F- groundwater worldwide.

Theoretical analysis of conduction-cooled current lead for superconducting magnet

CCCL is a typical CL type to energise SC magnets from room to cryogenic temperatures (<100 K) for its simplicity and reliability, but causes a relatively large heat leak (∼50 W kA−1 from 300 K) compared to the heat leak (∼1.0 W kA−1 from 300 K to liquid helium) of VCCLs, which necessitates a comprehensive understanding of designers and users. However, systematic studies on CCCLs are still lacking up to now. This study starts from the differential equation governing heat conduction and generation in CCCLs and firstly derives a completely exact theoretical solution by adopting the WFL law for thermal conductivity and electrical resistivity with temperature dependence. The solution facilitates the CCCL design optimisation to achieve the minimum heat leak, which is determined only by the temperature range but independent of both materials and geometrical parameters. Practical optimum designs are concerned with material properties and approached by calculating a shape factor to determine the conductor length and cross-sectional area, which is detailed and illustrated in this paper. Furthermore, the practical behaviours at low and excess currents can also be mathematically deduced, and the corresponding heat leaks are found to rely on materials but not on geometrical parameters. This paper also describes the agreements between the theoretical analysis and the numerical simulation and comparison with material properties of the non-WFL law.